1. Field of the Invention
The present invention relates to a method and apparatus for automated scanning of microscope slides and more particularly it relates to an automated slide scanning system with a focusing unit suitable for use in automated screening or prescreening of samples.
2. Background of the Invention
Traditional approach of slide scanning system for microscope includes an automated slide loader with slides holder and a motorized scanning (X-Y) stage for scanning the slides. Typically, the motorized X-Y microscope stage includes means for moving the slide relative to a microscope objective on two orthogonal (X and Y) axes to provide precise positioning of the slide, and possibly also on a third orthogonal (Z) axis to provide automatic focusing. Such systems can also be equipped with slide positioning stages to facilitate the positioning of successive slides and removing and storing them after scanning.
The slide scanning systems known in the prior art are typically bulky and heavy requiring a considerable amount of space. In addition, such systems are expensive, unreliable and complicated requiring a precise alignment and interface of the slide loader and the microscope. The focusing of such prior art scanning systems includes a screw or rack-and-pinion focus adjustment which causes backlash and hysteresis of the focusing unit. The transfer of the slides from the loader to the microscope can occasionally fail causing the system halt and slide damage during transfer. In most of the known prior art slide scanning systems, slides are stored vertically providing poor visibility of slide's labels. Also, with vertically stored slides systems manual retrieval of a specific slide is not a simple task because the slide labels are not clearly visible.
Accordingly, there is a need for a slide scanning device that is simple, reliable and low cost, and that mitigates the problems of the prior art. This can be achieved by departing from the traditional loader/microscope setup and by combining all functions of slide scanning system in one, simple device.
Other limitations of the prior art will become apparent upon reading the specification and study of the drawings.